One of the most challenging MMOs I've ever played.
It's an MMO, yet it's a challenge to make characters on the same server as your friends and then it's a challenge to log on and play with them. Hell, it's a challenge to even start in the same city since you are pigeonholed into one class/role/city. This is actually the first MMO I've ever played where I can't really make a NA character even if there is an open server because chances are my friends will not be able to make a character on that server for whatever reason so there is no point. It's a challenge to not get bored wasting time on JP servers knowing that it's all for naught. It's fun feeling paralyzed, like you are taking a risk making a "main" character since chances are high you are wasting your time with it and will have to throw it away when you reroll.
It's becoming a challenge to even attempt logging on.